It is common practice in the design and manufacture of artificial limbs to take plaster impressions of the affected limb, and to make a positive plaster model from the impression. This process of measurement and construction is not very accurate, or repeatable, and the artificial limb maker (prosthetist) is given no information on the exact location of the bone within the limb tissue. However, it is the location of the bone and its relation to the limb tissue which determines the final shape of the artificial limb socket, since the bone and tissue are used to help support the artificial limb on the amputated stump. The primary limitations impeding a good fit are the high cost associated with each test fit and the skill level required by the artificial limb maker. Many trial sockets may be required to provide a comfortable fit for an amputee with cost being proportionate to the number of fittings.
In recent years, several attempts have been made at automating the artificial limb design and manufacturing process, but none characterize the location of the bone in relation to the limb tissue. This results in an ineffective and usually painful fit for the artificial limb socket to the amputee, and, as a consequence, the socket is discarded. In addition, there is no complete system that both accurately and automatically measures the limb and provides a direct interface to a numerically controlled milling machine for the artificial limb socket manufacturer. Finally, the current process provides no way of conveniently saving the results of the final prosthetic socket model. The current process produces a plaster model that is destroyed as pan of the artificial limb socket construction process. Thus, when the original socket becomes worn or ill-fitting with use (the amputee's stump normally changes size and shape as tissues shrink during the first few years of wearing a prosthesis) and a new socket is necessary, the process must start all over from an initial plaster impression.
There continues to be a need for rapid design and production of artificial limbs, because in the United States alone there are approximately 50,000 limb amputations performed every year. Therefore those concerned with the rehabilitation of these people have often requested a more rapid, reliable and economical system for the design and manufacture of artificial limbs. The method and apparatus of the present invention, discussed in greater detail below, clearly fulfills those needs.